Zoysia grass, which is a perennial herb, belongs to Graminae family, and propagates by stolons and rhizomes, showing wide variation in its morphology and other characteristics, according to regions. It has been reported that there are, in Korea, five or six species of zoysia grasses including Z. japonica, Z. matrella, Z. tenufolia, Z. sinica and Z. macrostachya. Zoysia grass, as a warm-season grass, widely grows wild in Far Eastern Asia including Korea, and is used in almost all places including gardens, parks, sports grounds, golf links, banks of roads, reclaimed lands, and airports. Especially, zoysia grass is well suited to Korean climate, and is superior in its adaptability to various environments to cool-season grasses and other warm-season grasses. In addition, zoysia grass is known to have strong resistances to drought, trampling, cold, heat, and salt. However, zoysia grass, commonly, has problems that its propagation is relatively slow and is green for a short period of time. In this regard, there is a need for development of cultivars of zoysia grass.
In Korea, 63 excellent grass species were selected from zoysia grasses collected from natural populations since 1965 in Korea, performed by D. Y. You and D. E. Yeam of Seoul National University. Thereafter, it was reported that Z. koreana of acinus form has rapid breeding and salt resistance properties, as disclosed by D. E. Yeam, Y. G. Joo, I. S. Han, et. al. who participated in the Zoysia germplasm resource investigation conducted by the USDA (United States Department of Agriculture) in 1982 (Yeam, et. al., 1986; Kim, 1989). However, between 1985 and 1994, there was almost no research on breeding of zoysia grasses in Korea, and from 1995, several universities and research institutes in Korea including Konkuk University, Dankook University, Turfgrass and Environment Research Institute of Samsung Everland Inc. began carrying out research on zoysia grasses obtained from Seoul National University. Although Korea is the home of zoysia grass herbs, utilization and development of novel cultivars of zoysia grass lags behind the USA or Japan.
With the announcement of United Nations Convention on Biological Diversity in 1992, a major content provision of which protects property right of innate seeds of individual nation, each nation of world has started to recognize the importance of its own genetic resources, resulting in that it will become gradually more difficult to export or distribute valuable genetic resources as well as genetic resources of which properties are unknown.
Among the zoysia grasses described above, Z. japonica is, in Korea, mainly used in golf links, sports grounds, or parks, and Z. matrella is partly used in warm regions of Korea. In spite of the wide uses of grass, in Korea, there is no systematic selection and breeding of cultivars of zoysia grass. Moreover, some advanced countries, such as the USA or Japan, have collected grasses naturally growing in Korea and other Southeast Asian countries, bred them, and selected excellent cultivars to sell them to other countries, resulting in their occupying a dominant position in international market. In contrast, especially in Korea, randomly selected and propagated zoysia grasses have been circulated, causing non-uniformity in the view that various species of grass are mingled without classification of species. In addition, the grasses produced in advanced countries are now market at a low cost. Therefore, it is urgently required to collect zoysia grasses with excellent genotypes and growth habit, and propagate zoysia grasses having excellent morphological and genotypic characteristics.